Old Faithful, Canyon, and Mammoth Hot Springs all have dining. There's got to be dining at Lake Lodge as well, but I just haven't been for a while and can't remember. The food, in my experience, isn't bad. It will be a little pricey. We tried the cafeteria / dining area at Canyon Lodge last September while were waiting out a blizzard. The food was good enough that we'd eat there again, if needed.

Overall, there's not a ton of options in the park for food, and there are a lot of sites / hikes that aren't near a dining option so we usually eat breakfast and dinner outside of the park and pack in our own food and picnic somewhere (or eat in the car at a trailhead).

West Yellowstone has some food options. Firehole BBQ (surprisingly good BBQ) is where we pick up food sometimes. It's about 30-minutes outside of West Yellowstone so out of the way a bit, but we love Campfire Lodge for breakfast. Huge portions (HUGE pancakes) and good cinnamon rolls. Plus, it's situated right on the Madison River so the views from the dining area are great.